Process for the preparation of the 21-acetate of 16, 17-oxido-11-dehydrocorticosterone



United States Patent 0 PROCESS FOR THE PREPARATIGN OF THE 21- ACETATE 0F 16,17-UXIDU-11-DEHYDRUCGR- TICOSTERUNE George I. Poos, North Piaintield, and Lewis H. Sarctt,

Princeton, N. 5., assignors to Merck & Co., Inc, Rahway, N. 3., a corporation of New Jersey No Drawing. Application June 30, 1954, erial No. 44%,550

3 Claims. (Cl. Zfilk-23955) This invention relates to steroids and in particular to 16,17-oxido-1l-dehydrocorticosterone esters, to processes for preparing these compounds and to intermediate compounds thus obtained.

The compounds which are the subject of the invention are 16,17-oxido-11-dehydrocorticosterone esters which have the following general formula:

CHzR

wherein R is an acyloxy group having a chain length of from 2 to 10 carbon atoms. These compounds may be readily converted to valuable steroids such as cortisone.

The 16,17-oxido-1l-dehydrocorticosterone esters are prepared by reacting 3-ethylenedioxy-n -pregnadiene- 11,20-dione (compound I) with hydrogen peroxide in the. presence of a base to produce 3-ethylenedioxy-l6,17-oxido- A -pregnene-11,20-dione (compound II). This compound is then treated with an organic oxalate in the presence of a basic substance to form the corresponding ester of 3- ethylenedioxy-16,17-oxidoA -pregnene- 11,20 dione 21- oxalyl acid (compound III) and also l7-hydroxy-2lb-carbomethoxy-16,2lb-y-pyrenone (compound IV). The ester of 3 ethylenedioxy-16,17-oXido-A -pregnene-l1,20-dione, 21-oxalyl acid is then hydrolyzed, treated with iodine in the presence of a base, and the resulting iodoketone is then reacted with a salt of acarboxylic acid to form a 2l-ester of 3-ethylenedioxy-16,17-oxido-A -pregnene-2l-ol- 11,20-dione (compound V). This latter compound may be subjected tohydrolysis to form the corresponding 21- ester of 16,17-oxido-1l-dehydrocorticosterone (compound VI).

As an alternate procedure, the 16,17-oxido-l l-dehydrocorticosterone esters may be prepared by reacting 3-ethylenedioxy-A 'pregnadiene-l1,20-dione (compound I) with an organic oxalate in the presence of a basic sub stance to form an ester of 3-ethylenedioxy-A -pregnadiene-l1,20-dione-21-oxaly1 acid (compound IX). This ester may be saponified to produce the corresponding acid (compound X). The 3-ethylenedioxy-A -pregnadiene- 11,20-dione-21-oxalyl acid is then treated with iodine in the presence of a basic substance and the resulting iodoketone is then reacted with a salt of a carboxylic acid to form a 21-ester of 3-ethylenedioxy-A -pregnadiene-Z1- ol-l1,20-dione (compound XI). This latter compound may then be reacted with hydrogen peroxide in the presence of a base to form the corresponding 2l-ester of 3- ethylenedioxy-16,17-oxido-A -pregnene-2l-ol-11,20 dione (compound V).

The 21-ester of 3-ethylenedioxy-16,17-oxido-A -pregnene-21-o1-11,20-dione may be converted to the corresponding cortisone ester (compound VIII) by hydrolytic cleavage with a halogen acid to produce the corresponding 21-ester of 16-halo-A -pregnene-l7a,2 l-diol-3,1 l-20-trione (compound VII) which is then subjected to reductive dehalogenation to form the cortisone ester. The 2l-ester of 16,17-oxido-1l-dehydrocorticosterone (compound VI) may be converted to the corresponding 2l-ester of cortisone (compound VIII) by hydrolysis with a halogen acid and reductive removal of the 16-halogen. These reactions may be chemically represented wherein R is an acyloxy group and R is an alkoxy group as follows:

Patented Oct. 15, 1957 H 0 O on; oHni-b-r: CHz-i'l-E-OH i=0 =0 ta,

0 [0 l:0 [O O O Compound I Compound IX Compound X CH: 0112B Compound XI Compound 11 The 3-ethylenedioxy-A -pregnadiene-11,20-dione may be converted to 3.-ethylenedioxy-16,17-oxido-A -pregnene- 11,20-dione by treating with hydrogen peroxide in the presence of a base. This reaction proceeds most favorably in a solvent such as methanol, ethanol, propanol, butanol or the like. The basic substance may be any of the conventional bases, such as the alkali metal hydroxides, carbonates or bicarbonates. Typical examples of such compounds are potassium hydroxide, sodium hydroxide, sodium carbonate, potassium carbonate and potassium bicarbonate. The reaction proceeds most favorably at room temperature in from 1 to hours. The product may be recovered by diluting the reaction medium with water which precipitates the product which may then be filtered from the solution. The product may be further purified by recrystallization.

The 3-ethylenedioxy-l6,17-oxido-A -pregnene-l1,20-dione is converted to the ester of 3-ethylenedioxy-l6,l7- oxido-A -pregnene-11,2O-dione-21-oxalyl acid by reacting with an organic oxalate in the presence of a basic substance. This reaction is preferably carried out under anhydrous conditions. The reaction proceeds most favorably when carried out in a solvent for the reactants. Suitable solvents are hexane, benzene, toluene, xylene, petroleum ether, ether, dioxane, tetrahydrofuran and the like. The basic substance may be any of the conventional bases such as an alkali metal or its hydroxide, hydride or alkoxide, but it is preferred to use an alkoxide, as for example sodium methoxide, sodium ethoxide, potassium methoxide or potassium ethoxide. The ester formed Will depend on the particular oxalate selected. Any of the oxalates may be used but it is preferred to use the lower dialkyl oxalates such as dimethyl oxalate and diethyl oxalate thereby forming the corresponding methyl or ethyl ester. The reaction proceeds favorably at room temperature in from 14 to 20 hours for completion although other temperatures, such as for 0 to 100 C. may be used. The reaction product is most conveniently separated from the reaction mixture by neutralizing the mixture by the addition of mineral or organic acid in theoretical amount such as sulfuric, hydrochloric, phosphoric or acetic acids or by the addition of an excess of an acidic butfer such as sodium dihydrogen phosphate and then extracting with a solvent such as chloroform. The extract containing the product may then be concentrated to dryness to remove the excess oxalate. A by-product of this reaction is the isomeric OHRR Compound VI Co pound vnr 17-hydroxy-2lb-carbomethoxy-l6,2lb-y-pyrenone which in itself is useful for producing other steroids.

The ester of 3-ethylenedioxy-16,17-oxido-A -pregnene- 11,20-dione-2l-oxalyl acid is converted to the 21-ester of 3-ethylene-dioxy-16,17-oxido-A -pregnene-2l-ol-l1,20- dione. The conversion is carried out by first reacting the oxalyl ester compound with iodine in the presence of a base followed by alkaline cleavage to form the corresponding 2l-iodo compound. The reaction is most conveniently carried out in methanolic sodium methoxide although other alcohols and alkali metal alkoxides may be used. One equivalent of base and iodine are added and then after rapid decolorization is complete another equivalent of base .is added. The reaction is complete after standing at 0 for 1 to 20 hours or at room temperature for /2 to 5 hours. After the reaction is complete the iodo compound may be recovered if desired by extracting with ether and then evaporating the ether. It is desirable in carrying out the reaction to protect the reaction mixture and the product from light in order to avoid decomposition of the product. The iodo compound is then reacted With an alkali metal salt of a carboxylic acid to form the corresponding 21-ester of 3 ethylenedioxy 16,17 oxido A pregnene 21 ol- 11,20-dione. Typical examples of suitable metal salts are sodium acetate, potassium acetate, sodium propionate and sodium benzoate. This reaction is conveniently carried out by heating a solution of the iodo compound dissolved in a suitable solvent such as acetone under reflux with a potassium .salt of a lower carboxylic acid for A to 4 hours. After completion of the reaction, the product is readily recovered by evaporating the solvent under diminished pressure, extracting the resulting residue with ether and then evaporating the ethereal extract.

The 21-ester o'f 3-ethylenedioxy-16,17-0xido-A -pregnene-21-ol11,20-dione is hydrolyzed to form the corresponding 2l-ester of 16,17-oxido-1l-dehydrocorticosterone. This hydrolysis is readily achieved by treating with an acid in a suitable solvent such as methanol, ethanol, acetone or tetrahydrofuran. Strong acids such as hydrochloric acid, sulfuric acid, perchloric acid and p-toluene sulfonic acid used in dilute concentrations are preferred for effecting the hydrolysis. Temperatures ranging from about 20 to C. are usually employed to accomplish the hydrolysis. At the reflux temperature of the solvent several minutes to one hour are ordinarily adequate for completing the reaction. The reaction, mixture, following completion of the reaction, may be diluted with water to precipitate the desired 2l-ester of 16 ,17-oxido-1l-dehydrocorticosterone which may be separated by filtration and then dried.

The 3-ethylenedioxy-A pregnadiene-11,20-dione is reacted with an organic oxalate in the presence of a basic substance to form the corresponding ester of 3-ethylenedioxy-A -pregnadiene-11,20-dione-2l-oxalyl acid. This reaction is generally-carried out under anhydrous conditions. The reactants are preferably brought together in a solvent. Suitable solvents are hexane, benzene, toluene, xylene, petroleum ether, ether, dioxane, tetrahydrofuran and the like. The basic substances may by any of the conventional bases such as, an alkali metal or its hydroxide, hydride or alkoxide, but it is preferred to use alkoxides, as for example, sodium' methoxide, sodium ethoxide, potassium methoxide or potassium ethoxide. The oxalyl ester which is formed will depend on the particular oxalate selected. Any of the oxalates may be used but it is preferred, however, to use the lower dialkyl oxalates such as, dimethyl oxalate and diethyl oxalate, thereby forming the corresponding methyl or ethyl ester. The reaction proceeds favorably at room temperature in from 14 to 20 hours although other temperatures, such as 0 to 100 C., may be used. The reaction product is most conveniently separated from the reaction mixture by neutralizing the mixture by the addition of mineral or organic acid in theoretical amount such as sulfuric, hydrochloric, phosphoric or acetic acids or by the addition of an excess of an acidic bufier such as sodium dihydrogen phosphate and then extracting with a solvent such as chloroform. The extract containing the product may then be concentrated to dryness to remove the excess oxalate.

The ester of 3-ethylenedioxy-A -pregnadiene-11,20- dione-Zl-glyoxalic acid may be converted to the corresponding acid by saponifying the ester. The Saponification of the ester may be carried out by treating with any base such as an alkali metal hydroxide, carbonate, alkoxide or the like. The reaction is preferably carried out in water in the presence of a solvent such as an ether or hydrocarbon with an alkali metal hydroxide. Typical examples of such solvents are methyl ether, ethyl ether, methyl ethyl ether, toluene and benzene. The acid salt thus formed may be treated with an acidic agent to form the 3-ethylenedioxy-A -pregnadiene-11,20-dione-21-oxalyl acid. Any acid may be used for this step but it is preferred to use an acidic buffer such as sodium dihydrogen phosphate. The acids are particularly useful in themselves for separating the racemic steroids into their optical antipodes. As for example, upon intimately contacting the racemic steroid acid with an optically active base in a suitable solvent medium, the acidic compound reacts with the base to form a mixture of the d and l salts which may be separated by fractional crystallization from suitable solvents.

The 3-ethylenedioxy-A -pregnadiene-11,20-dione-21- oxalyl acid is converted to the 2l-ester of 3-ethylenedioxy- A -pregnadiene-2l-ol-l1,20-dione. This conversion is carried out by first reacting the 3-ethylenedioXy-A pregnadiene-l1,20-dione-21-oxalyl acid in a mildly alkaline solution such as aqueous disodium hydrogen phosphate with iodine. The reaction is completed by adding a strong base such as potassium hydroxide and allowing the reaction mixture to stand at approximately 0 to 25 C. for about /2 to 20 hours. The iodo compound may then be recovered if desired by extracting with ether and then evaporating the ether solution to dryness. It is desirable in carrying out the reaction to protect the reaction mixture and the product formed from light in order to avoid decomposition of the product. The iodo compound is then reacted with an alkali metal salt of a carboxylicaeid to form the corresponding 21-ester of 3- ethylenedioxy-A -pregnadiene-21-o1-11,20-dione. Typical examples of such salts are sodium acetate, potassium. acetate,'sodium propionate and sodium benzoate. This.

reaction is preferably carried out by heatinga solution of the iodo compound dissolved in acetone under reflux with a potassium salt of a lower carboxylic acid for about /4 to 4 hours. The product may be readily recovered by evaporating the solvent under diminished pressure, extracting the resulting residue with ether and evaporatihg the ethereal extract.

The 21-ester of 3-ethylenedioxy-A -pregnadiene-21- ol-l 1,20-dione may be converted to the corresponding 21- ester of 3 ethy1enedioxy-16,17-oxido-A -pregnene-2l-ol- 11,20-dione by treating with hydrogen peroxide in the presence of a base. This reaction proceeds most favorably in a solvent such as methanol, ethanol, propanol, butanol, or the like. The base may be any of the basic substances such as alkali metal hydroxides, carbonates or bicarbonates. Typical examples of such compounds are potassium hydroxide, sodium hydroxide, sodium carbonate, sodium bicarbonate and potassium bicarbonate; The reaction proceeds most favorably at room temperature in from 1 to 20 hours. The product may then be recovered by diluting the reaction medium with water which precipitates the product which may then be filtered from the solution. The product may be further purified by recrystallization.

The 21-ester of 3-ethylenedioxy-16,17-oxido-A -pregnene-2l-ol-l 1,20-dione may be converted to the 21-ester of 16-halo-A -pregnene-17u,21-diol-3,11-20 trione by cleavage of the oxide function with hydrogen halides. Although hydrochloric and hydroiodic acids may be used, it is preferred to use hydrobromic in the presence of a suitable solvent such as acetic acid or propionic acid. The reaction proceeds rapidly at room temperature although increased reaction time and elevated temperature may be employed. The reaction product can be recovered by filtration or by dilution of the reaction mixture with water and extraction with a suitable solvent such as chloroform.

The 2l-ester of the 16-halo-A -pregnene-17a,21-diol- 3,11,20-trione i then reduced to form the corresponding ester of cortisone. Although a variety of mild chemical and catalytic reducing methods may be employed, it is preferred to treat the 16-bromo-2l-ester of cortisone with nickel catalyst in a boiling solvent such as ethanol. The product may be recovered by filtration from the catalyst and concentration of the solvent.

The following examples are given for purposes of illustration.

Example 1 One milliliter of 2 N sodium methoxide was concentrated to dryness and the residue was heated briefly at C. under vacuum. To this dried sodium methoxide were added 300 mg. of dimethyl oxalate, 3 ml. of dry benzene and 250 mg. of 3-ethylenedioxy-A pregnadiene- 11,20-dione. The reaction flask was stoppered tightly and the contents were stirred at room temperature overnight. A mixture of excess sodium dihydrogen phosphate and chloroform was added to the reaction vessel with rapid stirring; the chloroform was withdrawn and the aqueous part was extracted with chloroform. The combined chloroform solution Was dried over magnesium sulfate and concentrated to dryness. The residue was warmed under high vacuum until all of the excess oxalate was removed. The crystals remaining were the methyl ester of 3-ethylenedioxy-A -pregnadiene-11,20- dione-21-oxalyl acid; purified by recrystallization from ethyl acetateether, melting point ISO- C., )t max. 305 me, E mol. 8,770.

Example 2 Saponification of the product of Example 1 by shaking a benzene-ether solution with 1 N potassium hydroxide gave the potassium salt and then acidification of the alkaline solution with sodium-dihydrogen phosphate and extraction with chloroform gave the 3-ethylenedioxy- A pregnadiene41,20 dione-21roxalyl acid, melting point 173-183 C. (dec.)'.

Example 3 A solution of 2.25 g. of disodium hydrogen phosphate in 50 ml. of water was overlayered with 4 ml. of ether containing 210 mg. of the methyl ester of 3-ethylenedioxy-A -pregnadiene-11,20-dione-21-oxalyl acid. The reaction mixture was stirred rapidly and treated dropwise with a solution of 118 mg. of iodine in ml. of ether. Five minutes after the addition of iodine was complete, 2 ml. of 1 N potassium hydroxide solution was added. The mixture was stirred briefly at room temperature and then stored overnight in the icebox. The reaction mixture was extracted with ether and the ether solution was dried and concentrated. The crude iodoketone obtained in this fashion was dissolved in 7 ml. of acetone and heated under reflux for one hour with 500 mg. of moist potassium acetate. After removing the acetone under vacuum, water was added and the organic material was extracted with benzene-ether. The benzene-ether solution was dried and concentrated and the product was recovered by chromatography over alumina. Elutionwith ether-chloroform gave 3-ethylenedioxy-A -pregnadiene-11,20-dione-21-ol-2l-acetate purified by recrystallization from ether; melting point 194- 197 C.: 206-208 C.; A max. 236 Ill 1., E mol. 8,770.

Example 4 To a solution of 500 mg. of 3-etl1ylenedioxy-A pregnadiene-11,20-dione in 30 ml. of methanol were added 1 ml. of 4 N sodium hydroxide and 3 ml. of 30% hydrogen peroxide. After two hours at room temperature, the reaction mixture was diluted to 100 ml. with icewater and the crystalline product which separated was collected on a filter, washed thoroughly with water and dried. Recrystallization from benzene gave pure 3-ethylenedioxy-l6,17-oxido-A -pregnene 11,20 dione, melting point 209-2l1 C.

Example 5 To the dried sodium rnethoxide from 1.5 ml. of a 1.90 N sodium methoxide solution were added 425 mg. of methyl oxalate, 5 mg. of dry benzene and 360 mg. of 3-ethylenedioxy-l6,17-oxido-A pregnene 11,20 dione. After one hour, excess sodium dihydrogen phosphate and chloroform were added to the reaction mixture and the aqueous part was extracted with additional cbloroform. The combined chloroform extracts were dried and concentrated and the residue was warmed under high vacuum to remove excess methyl oxalate. Purification of theproduct by recrystallization from benzene gave methyl ester of 3-ethylenedioxy-l6,l7-oxido-A -pregnene- 11,20-dione-21-oxalyl acid, melting point 177-182" C., max. 287.5 m E mol. 8,090. Extension of the reaction time resulted in the production of the isomeric l7-hydroxy-2lb-carbomethoxy-l6,21b-pyrenone as a second product which could be purified by recrystallization from benzene. The melting point of the compound was 254 to 256 C., max. 228 m E mol. 8,000.

Example 6 A suspension of 340 mg. of the methyl ester of 3- ethylenedioxy 16,1" oxido A -pregnese 11,20 dione- 21-oxalyl acid in 10 ml. of methanol was cooled to 0 C. and then with stirring treated first with 0.3 ml. of 2 N sodium methoxide solution and then a solution of 180 mg. of iodine in 10 ml. of methanol. After ten minutes at 0 C. an additional 0.4 ml. of 2 N sodium methoxide was added and the reaction mixture was allowed to stir cold for two hours. Twenty milliliters of water was added and the methanol was distilled under vacuum. The aqueous residue was extracted with chloroform and the chloroform solution was dried and concentrated. The crude residual iodo-ltetone was dissolved in ml.

of acetone and'heated under reflux for one hour with l g. of moist potassium acetate. Inorganic salts were separated by filtration and the. filtrate was concentrated to dryness. The residue was dissolved in chloroform, washed with water, dried and concentrated. Chromatography of the residue over alumina gave in the benzene eluate 3-ethylenedioxy-l6,17-oxido-A -pregnene-21- ol-ll,20-dione 21-acetate; purified by recrystallization from ether, melting point 193194 C.

Example 7 Twenty milligrams of: 3-ethylenedioxy-l6,17-oxido-A pregnene-Zl-ol-l1,20-dione 21-acetate in 2.5 ml. of acetone containing 0.03 ml. of 78% sulfuric acid was heated under reflux for 15 minutes. The reaction mixture was diluted with water, the acetone was evaporated and the aqueous residue was extracted with ethyl acetate. The ethyl acetate solution was dried over magnesium sulfate and concentrated. Crystallization of the residue from ethyl acetate gave pure dl-16,l7-oxido-l l-dehydrocorticosterone acetate, melting point 214-216 C.

Example 8 Forty-five milligrams of 3-ethylenedioxy-l6,17-oxido- A -pregnene-2l-ol-11,20-dione 21-acetate was suspended in 0.4 ml. of acetic acid. The mixture was chilled to ca. 15 C. and treated with 0.1 ml. of 32% hydrogen bromide in acetic acid. Dissolution of the starting compound was soon followed by crystallization of the product. After 15 minutes, the mixture was cooled and the crystals were collected, washed with acetic acid and ether and dried. The product, 16-bron1ocortisone acetate, could be purified by recrystallization from benzene; melting point 235-240 C. (dec.).

A solution of 35 mg. of 16-brorno-cortisone acetate in 3 ml. of ethanol was heated under reflux with mg. of Raney nickel for seven hours. After filtration from the catalyst, concentration of the ethanol gave a lcortisone acetate.

Any departure from the above description which conforms to the present invention is intended to be included within the scope of the claims.

What is claimed is:

l. The process which comprises reacting 3-ethylenedioxy-o -pregnadiene-11,20-dione with dimethyl oxalate in the presence of a basic substance to form the methyl ester of 3-ethylenedioxy-A -pregnadiene-l1,20- dione-Zl-oxalyl acid, reacting this latter compound with iodine in the presence of a base, treating the resulting product with an alkali metal salt of acetic acid to form the corresponding 21-acetate of 3-ethylenedioxy-A pregnadiene-l1,20-dione, reacting this compound with hydrogen peroxide in the presence of a base to form the corresponding 21-acetate of 3-ethylenedioxy-l6,17-oxido- A -pregnene-21-ol-11,20-dione and treating this latter compound with acid to form the 2l-acetate of 16,17-oxido-l1-dehydrocorticosterone.

2. The process which comprises reacting 3-ethylenedioxy-A -pregnadiene-11,20-dione with hydrogen peroxide in the presence of a base to form 3-ethylenedioxy- 16,17-oxido-A -pregnene-11,20-dione, reacting this compound With dirnethyloxalate in the presence of a base to produce the methyl ester of 3-ethylenedioxy-16,17- oxido-M-pregnene-l1,20-dione-2l-oxalyl acid, treating said ester with iodine in the presence of a base and reacting the product thus formed with an alkali metal salt of acetic acid to form the 2l-acetate ester of 3-ethylenedioxy 16,17 oxido A pregnene-Zl-ol-l1,20-dione and treating the latter compound with acid to form the 21- acetate of 16,17-oxido-1l-dehydrocorticosterone.

3. The process which comprises reacting the methyl ester of 3-ethylenedioxy-16,17-oxido-A -pregnene-l1,20- dione-ZI-Oxalyl acid with iodine in the presence of a base, reacting the resulting compound with an alkali metal salt of acetic acid to form the ZI-acetate ester of 3-ethylene- Refernces Cited in the file of this patent UNITED STATES PATENTS Julian Aug. 10, 1954 Hogg June 12, 1956 10 Erhart et a1 June 26, 1956 Farrar Aug. 21, 1956 OTHER REFERENCES Julian, pp. 195201. Recent Progress in Hormone Re- 7 search, vol. VI, (1951). 

1.THE PROCESS WHICH COMPRISES REACTING 3-ETHYLENEDIOXY-$5.16-PREGNADIENC-11,20-DIONE WITH DIMETHYL OXALATE IN THE PRESENCE OF A BASIC SUBSTANCES TO FROM THE MENTHYL ESTER PF 3-ETHYLENEDIOXY-$5.16-PREGNADIENE-11,20DIONE-21-OXALYL ACID REACTING THIS LATTER COMPOUND WITH IODINE IN THE PRESENCE OF A BASE, TREATING THE RESULTING PRODUCT WITH AN ALKALI METAL SALT OF ACETIC ACID TO FROM THE CORRESPONDING 21-ACETATE OF 3-ETHYLENEDIOXY-$5,16PREGNADIENCE-11,20-DIONE, REACTING THIS COMPOUND WITH HYDROGEN PEROXIDE IN THE PRESENCE OF A BASE TO FROM THE CORRESPONDING 21-ACETATE OF 3-ETHYLENEDIOXY-16,17-OXIDO$5-PREGNENE-21-11,20-DIONE AND TREATING THIS LATTER COMPOUND WITH ACID TO FROM THE 21-ACETATE OF 16,17-OXIDO-11-DEHYDROCORTICOSTERONE. 